Cache package lookups

src/rules/no-internal-import.js

@@ -2,10 +2,10 @@ import moduleVisitor, {
   makeOptionsSchema,
 } from 'eslint-module-utils/moduleVisitor';
 import parse from 'parse-package-name';
-import getPackages from 'get-monorepo-packages';
 import path from 'path';
 import minimatch from 'minimatch';
 import fs from 'fs';
+import getPackages from '../util/get-packages';
 
 export const meta = {
   schema: [makeOptionsSchema({})],

src/rules/no-relative-import.js

@@ -5,7 +5,7 @@ import moduleVisitor, {
 import isInside from 'path-is-inside';
 import minimatch from 'minimatch';
 import path from 'path';
-import getPackages from 'get-monorepo-packages';
+import getPackages from '../util/get-packages';
 
 export const meta = {
   schema: [makeOptionsSchema({})],

src/util/get-packages.js

@@ -0,0 +1,15 @@
+import getPackages from 'get-monorepo-packages';
+
+const packageMap = new Map();
+
+export default function getPackagesWithCache(directory) {
+  // We assume that the set of monorepo packages for this directory will
+  // not change during a single eslint run
+  let packages = packageMap.get(directory);
+  if (!packages) {
+    packages = getPackages(directory);
+    packageMap.set(directory, packages);
+  }
+
+  return packages;
+}